Acrylic sheet to replace glass in carrier?

I've had problems with a rebate reflection in my negative carrier, which I've discovered is caused by the bottom sheet of glass.
Would a piece of acryllic of the same thickness and size, with a 6cm square hole for the negative, be an adequate replacement?

In particular I'm wondering about damage the acrylic might cause to the negatives (acid?), as well as potential flexing when the acrylic is warmed by the lamp and then cooled.

Without knowing more about the model of enlarger and details of the negative carrier, I'm wondering (speculating) if the problem is not the glass itself but that the glass is diffracting a reflection source from the tracks in the carrier? I'd want to check for any bright spots that may be the results of wear between the carrier and the tracks it slides in.

Use Lexan polycarbonate sheets. I replaced a bottom diffuser in a mixing box of an enlarger that has a 200W 24V bulb with a 2mm Lexan sheet and it passed the several-hour test. It is milky white, though, and very hard and glossy on one side while the other is slightly matt. There are clear versions available and likely free - ask for samples (mine's a sample). They deliver them protected on both sides.

Neither acrylic nor polycarbonate will remain flat without bowing, so would be worthless in a neg
carrier. Stray light can be masked off. Or if it's bouncing off the actual edges of the glass, simply
paint these with a stroke of a black Magic Marker or Sharpie pen.

That looks very similar to a Durst carrier, Durst blackened the beveled edges at the factory on the glass inserts I have. Those glass inserts look a little too thick as well, they should just be a tiny bit proud of the metal frame. You could make an aluminum insert for a glassless carrier, I did that with 1.5mm thick aluminum sheet for both the lower and upper glasses on the D659 enlarger. File out the hole to match your negative image area. The D606 and others use the same 1.5mm glass inserts.

They are pretty thick. There's an extra, thinner piece of glass that came with the enlarger, which I really can't get my head around. Obviously this doesn't sit flat with the thicker top piece and neither does it solve the reflection problem. My enlarger is a Krokus 3 by the way.

I'd be very worried about scratches to the negative with aluminium, even if I was extra careful filing. Isn't this a problem with yours?